This invention relates to semi-synthetic .beta.-lactam antibiotic compounds, compositions thereof, a method for combating infectious bacteria, and to intermediates useful in the preparation of the antibiotic compounds. In particular, it relates to .beta.-lactam compounds substituted by a thiazolium or substituted thiazolium group.
Numerous cephalosporin antibiotics having a quaternary amino or betaine structure at the 3'-position of the 3-cephem ring system have been described since Abraham et al. described cephalosporin C.sub.a (pyridine), Hale, Newton, and Abraham, Biochem. J., 79, 403 (1961). One such quaternary ammonium substituted cephalosporin known as cephaloridine, 7-(2-thienylacetylamino)-3-(pyridinium-1-ylmethyl)-3-cephem-4-carboxylate, has achieved clinical importance as an antibotic. Other recent quaternary ammonium substituted cephalosporins of commerical interest include that described by Ochiai et al., 7-[2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-(pyridinium-1-ylmeth yl)-3-cephem-4-carboxylate, in U.S. Pat. No. 4,278,671 and ceftazidime, 7-[2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-yl)oxyiminoacetamido]-3-(pyr idinium-1-ylmethyl)-3-cephem-4-carboxylate, in U.S. Pat. No. 4,258,041.
Because of the interesting antibacterial properties of cephalosporin substituted with a quaternary ammonium group, extensive research continues to discover new .beta.-lactam antibiotics with greater potency against various microorganisms.